Some 200 lawmakers from 80 countries were sharply divided over how to stem spiralling healthcare costs caused by poor diets at the first global parliamentary summit against hunger and malnutrition, which ended on Tuesday.

"Education is not enough. We need to use laws," said Guido Girardi, a Chilean senator and doctor who authored a landmark 2016 law that mandates comprehensive labelling of foods that are high in sugar, salt, saturated fats and calories.

Unhealthy products also cannot be advertised on Chilean television or the internet, or use toys, cartoons or stickers to encourage children to eat them, said Girardi.

Supporters hail the law, but critics say it impinges on consumer choice, in a battle that is set to heat up as governments seek to improve people's eating habits in the face of resistance from food and drink manufacturers.

One in nine people around the world goes hungry every night, while one in eight adults are obese, according to the latest figures from the United Nations.

Jose Graziano da Silva, director-general of the U.N. Food and Agriculture Organization (FAO) warned of "the globalisation of obesity" affecting both rich and poor countries at the summit's opening on Monday.

"If we do not find concrete ways to stop this constant increase, the number of obese people will soon be as high as the number of people who are hungry," he said.

More than a dozen governments have taxed sugary drinks and food high in salt and fat.

But Paolo De Castro, Italy's former agriculture minister and a European parliamentarian, said colour-coding food according to its nutritional content was "a mistake".

"Good food, bad food, it doesn't exist. It depends on how much you eat," he told the Thomson Reuters Foundation.

"We need to give education to the people. We don't have to (regulate) choice. In my mind, that is totally wrong."

He pointed to a European Union school scheme, which gives students fruits, vegetables and milk while teaching them about nutrition, as a possible solution.

But Xochitl Galvez Ruiz, a senator in Mexico - which has one of the world's highest diabetes rates - said she will continue to push for a food labelling law similar to Chile.

"We've done it before with the tax on sugary drinks and saw that it worked," she said.

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